Amelioration of today’s drug problem requires Americans to understand the significance of the 80/20 ratio. Twenty percent of American drinkers consume 80 percent of the alcohol sold here. The same 80-20 split obtains among users of illicit drugs.

About 3 million people — less than 1 percent of America’s population — consume 80 percent of illegal hard drugs. Drug-trafficking organizations can be most efficiently injured by changing the behavior of the 20 percent of heavy users, and we are learning how to do so. Reducing consumption by casual users will not substantially reduce the northward flow of drugs or the southward flow of money.

Americans’ experience with marketing’s power inclines them to favor prohibition and enforcement over legalization and marketing of drugs. But this choice has consequences: More Americans are imprisoned for drug offenses or drug-related probation and parole violations than for property crimes.

And although America spends five times more jailing drug dealers than it did 30 years ago, the prices of cocaine and heroin are 80 percent to 90 percent lower than 30 years ago.

And imprisoning large numbers of dealers produces an army of people who, emerging from prison with blighted employment prospects, can only deal drugs. Which is why, although a few years ago Washington, DC, dealers earned an average of $30 an hour, today they earn less than the federal minimum wage ($7.25).

Dealers, aka “pushers,” have almost nothing to do with initiating drug use by future addicts; almost every user starts when given drugs by a friend, sibling or acquaintance. There is a staggering disparity between the trivial sums earned by dealers who connect the cartels to the cartels’ customers, and the huge sums spent trying to slow the flow of drugs to those street-level dealers.

Kleiman et al say that in developed nations, cocaine sells for about $3,000 per ounce — almost twice the price of gold. And the supply of cocaine, unlike that of gold, can be cheaply and quickly expanded. But in the countries where cocaine and heroin are produced, they sell for about 1 percent of their US retail price.

If cocaine were legalized, a $2,000 kilogram could be FedExed from Colombia for less than $50 and sold profitably in America for a small markup from its price in Colombia, and a $5 rock of crack might cost 25 cents. Criminalization drives the cost of the smuggled kilogram in America up to $20,000. But then it retails for more than $100,000.

People used to believe enforcement could raise prices but doubted that higher prices would decrease consumption. Now they know consumption declines as prices rise but wonder whether enforcement can substantially affect prices.

They urge rethinking the drug-control triad of enforcement, prevention and treatment because we have been much too optimistic about all three.

Cartels have oceans of money for corrupting enforcement because drugs are so cheap to produce and easy to renew. So it is not unreasonable to consider modifying a policy that gives hundreds of billions of dollars a year to violent organized crime.

Marijuana probably provides less than 25 percent of the cartels’ revenues. Legalizing it would take perhaps $10 billion from some bad and violent people, but the cartels would still make much more money from cocaine, heroin and methamphetamines.

Sixteen states have legalized “medical marijuana.” In 1990, 24 percent of Americans supported full legalization. Today, 50 percent do. In 2010, in California, where one-eighth of Americans live, 46 percent of voters supported legalization, and some opponents were marijuana growers who like the profits from prohibition.

Would the public-health problems resulting from legalization be a price worth paying for injuring the cartels and reducing the costs of enforcement? We probably are going to find out.